I have a male cat (4 years old, indoor, fixed) that presents several problematic behaviours. I have tried without avail to fix these behaviours so I am turning to the community for help.

First of all I want to say that he has plenty of amenities available to him (cat tree, toys, plenty of hiding spots around the apartment) and we play with him for at least 20 minutes a day, often more, and give him plenty of affection. His favorite games are to chase twine or feather rods, and catching treats we throw for him. Here are his behavioural issues;

He scratches furniture CONSTANTLY, despite having a designated scratching post and cat tree. We hit him with a squirt bottle whenever he does this, but it only stops momentarily.

He often attacks our other cat, a female. We have distanced their feeding area and litter boxes as much as possible. He is always the aggressor and our female is very timid and non-aggressive, so she copes with this by hissing and running away. When we notice this we separate them. So far no injuries have resulted from these attacks, but it is very stressful for her.

He will often scratch and bite us while we are petting him. When he bites me I will stick a finger in his mouth and when he scratches I will stop petting him or push him away (gently). There is no rhyme or reason for when he bites that I can tell- no areas of his body that trigger an attack, but once he gets into 'attack mode' he can be fairly aggressive and it hurts.

He is a very high-energy cat and needs lots of stimulation, but no matter how much he gets he is still unsatisfied and aggressive. How can I help him chill out?